USMLE and COMLEX Prep: Chemical Composition of Gallstones

Session 43

A 32 y/o woman with acute cholecystitis has a past medical history of acute hemolytic anemia. Which substance is likely to be found in her gallstones?

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[04:27] Question of the Day

A 32-y/o woman complains of right upper quadrant pain that is sharp and severe and has been worsening over the last six hours. Her oral intake worsens with her symptoms. Her past medical history includes systemic lupus, autoimmune hemolytic anemia, gout, membranoproliferative glomerulonephritis, and thrombocytopenia.

Physical exam reveals tenderness to palpation at the right upper quadrant. Imaging is performed and confirms a diagnosis of acute cholecystitis. The patient undergoes a laparoscopic cholecystectomy without any complications. The patients’ gallstones are most likely composed of which of the following substances?

(A) Calcium bilirubinate

(B) Calcium phosphate

(C) Calcium oxalate

(D) Cholesterol

(E) Uric acid

[05:25] Thought Process

She’s got a very complicated medical history and that’s going to have to play in here. Calcium oxalate refers to kidney stones and uric acid is also related to kidney stones so they’re crossed off at this time.

The most common gallstones are usually comprised of cholesterol. So the correct answer here is D.

Because of past medical history, there are things she will be more likely to have. There’s also sort of a red herring. The woman has gout and then you might think of uric acid.

They’re trying to trick you because uric acid is not going to create any gallstones or other types of stones. They create deposits in your joints but it won’t definitely give you the gallstones.

Similarly, a person with glomerulonephritis can predispose you to have higher levels of different circulating electrolytes. But then again, they should not create these types of stones.

Calcium oxalates are very common in kidney stones, which are going to present very differently. They’re going to be this blank pain and potentially some blood in the urine. But this is very clearly stone in her gallbladder.

Another thing to highlight here is the autoimmune hemolytic anemia. It’s not uncommon for these things to precipitate into the stones and the gallbladder. So it’s not uncommon for people with this condition to have these types of stones.

[10:52] Final Thoughts

Know the colors of stones especially for the kidney stones. Know what the shapes are under the microscope.